This invention relates generally to fasteners and more particularly to a fastener assembly comprising a screw and a captive compression spring.
The use of a compression spring as a locking member for a screw fastener is generally known in the prior art. For example, such an arrangement is commonly utilized as an adjustable idle screw for automotive carburetors, as it provides a considerable range of adjustment by allowing variable degrees of advancement of the screw with respect to its screw threads. The compression spring acts to maintain the screw at a desired degree of advancement, substantially preventing further rotation of the screw in either direction as might occur, due to vibration or the like.
Heretofore, however, these screws and springs have been provided separately by the manufacturer or manufacturers. Consequently, the screw fastener and spring must be assembled by a worker during the manufacture or assembly of a device such as a carburetor with which the screw and coil spring assembly is to be utilized. Accordingly, it is possible for the installer or assembly line worker to choose the wrong combination of screw and compression spring for installation, or improperly assembly or even neglect or forget to assemble the compression spring with the screw member prior to installation thereof. Thus, provision of a fastener assembly comprising a screw member with a captive compression spring member substantially eliminates these problems and facilitates the assembly operation. Moreover, it will be appreciated that such provision of a captive compression spring member is advantageous to the ultimate user in that it saves considerable time and trouble involved in selecting complimentary screw members and spring members independently and often from different manufacturers, and in providing a reliable supply of such properly selected and mated parts at the point of ultimate assembly and/or installation.
Accordingly, it is a general object of this invention to provide a fastener assembly comprising a screw member and a captive compression spring member.
A more specific object of this invention is to provide a fastener assembly of the type described wherein both screw and compression spring to the specifications of the user may be readily and easily selected and pre-assembled.
Another object is to provide a fastener assembly of the type described which may be relatively simply and inexpensively manufactured, assembled by even relatively unskilled workers, and yet remains relatively rugged and reliable in operation.
Briefly, and in accordance with the foregoing objects, a fastener assembly according to this invention comprises a screw member including a driver head, a threaded shank portion and an unthreaded shank portion intermediate said driver head and said threaded shank portion. A generally helical elongate compression spring member cooperates with protrusion means on said unthreaded shank portion so as to hold at least an end portion of said compression spring member in captive relation on said screw member, substantially coaxially therewith.
Other objects, features and advantages of this invention will become more readily apparent upon consideration of the following detailed description of the illustrated embodiment, together with the accompanying drawings.